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room for horizontal boring equipment, and the pipelines will either be trenched or bored under these features.
<br />Because pipeline placement and construction of portions of the 6RT, 7RT, 1MN, 2MN, and SWMD pads will
<br />necessarily involve activities within the Foidel Creek buffer zone, TC is requesting a temporary variance for
<br />pipeline construction and a longer-term variance for the limited pad areas from the regulatory requirements for
<br />operations within a buffer zone. The pipelines will be a double HDPE pipe system in critical areas (note that entire
<br />6RT, 7RT, 2MN, and SWMD pipelines will be double -pipe systems), with a 6 to 8- inch carrier pipe inside a larger
<br />(maximum size - 12 -inch diameter) containment pipe, buried approximately 5 -feet deep. The 1 MN pipeline will
<br />extend approximately 1,800 feet, with the 6RT pipeline extending approximately 8,000 feet, and continuing another
<br />1,600 feet to 7RT. The 6RT/7RT pipeline is immediately adjacent to the 21VIN Borehole, so only a short connecting
<br />pipe was necessary. The SWMD pipeline will extend approximately 7,700 feet from the SWMD Borehole,
<br />connecting into the iMN TUF Pipeline, and will generally fall within the previous disturbance areas for the
<br />Haulroad C corridor and the 18 -Left Mine Water Transfer Pipeline. Limited areas of pipeline construction will fall
<br />within the Foidel Creek Stream Buffer Zone, and both general and specific BMP's will be used to prevent adverse
<br />impacts to the hydrologic balance. The Sandstone Sub pipeline will extend approximately 1,200 feet from the i MN
<br />Borehole location. Electronic moisture sensors, along with pump controls, and shut-off valves provide for timely
<br />detection. shut-off, and isolation of the pipeline in the event of pipeline leakage. Access/inspection manholes and
<br />pipe -tees for the moisture detection system will be located at key points along the pipeline routes.
<br />During construction, and for the minor surface structures that will remain during mining, drainage and sediment control
<br />will be provided by Alternative Sediment Controls (ASC's) consisting of combined Best Management Practice (BMP)
<br />measures. As appropriate, ASC designs are included in the design exhibits for each installation. BMP's for the
<br />construction activities include (BMP's for any stream buffer zone areas include the general BMP's identified, as well as
<br />specific BMP's* as noted):
<br />• Minimizing the area of surface disturbance
<br />• Placement of stream buffer zones markers prior to disturbance in or immediately adjacent to buffer zone areas*
<br />• Scheduling of construction activities during the dry summer or early winter periods
<br />• Placement of staked straw wattles, silt fencing, or plastic silt barrio materials downgradient of all surface
<br />disturbance areas to intercept any surface runoff and trap associated suspended solids
<br />• Installation of the Foidel Creek, RCR27, and railroad spur pipeline crossings as either trenched or bored/jacked
<br />pipeline crossings under Foidel Creek, RCR27 and the railroad spur (if trenched, TC will obtain required
<br />CDPHE-WQCD Temporary Construction Discharge Permit and will complete required USACE notification
<br />• Windrowing or soil and excavated materials immediately adjacent to the pipeline trench, and progressive
<br />backfilling and soil replacement as pipeline installation proceeds
<br />• Restrictions on storage or transfers of petroleum products within or immediately adjacent to buffer zone areas*
<br />• Soil replacement and stabilization with either the standard rangeland or riparian seed mixtures (as appropriate)
<br />in a timely manner following completion of construction activities
<br />Construction -related surface disturbance will be limited to soil removal and windrowing from the pipeline trench
<br />alignments and stockpiling for the borehole pad areas, excavation of the trenches and temporary stockpiling of
<br />excavated material adjacent to the trenches, minor cut/fill grading to establish the borehole drill -pads and excavation of
<br />temporary cuttings pits, and excavation of temporary pits (within existing disturbance areas) for pipeline boring or
<br />jacking operations at the Foidel Creek, RCR27, and railroad spur pipeline crossings.
<br />Where pipeline disturbance traverses steep slopes, additional staked straw wattles will be placed on -contour to limit
<br />overland flow following revegetation seeding. Drainage and sediment control for the associated minor surface
<br />structures (borehole surface casings and any manhole(s)) will also utilize BMP's including the vegetative filter
<br />provided by temporary vegetative stabilization, and beans and/or wattles, as appropriate. The pads and access road for
<br />the 6RT, 7RT, 1 MN, 21VIN, and SWMD thickener underflow borehole installations have been designated as Small Area
<br />Exemptions (SAE's), and the limited drainage from these areas will be controlled by gravel surfacing, staked straw
<br />wattles, and reclamation/stabilization of the pad areas following well installation. SAE designs for these installations
<br />are provided in Exhibit 49S, and include upstream and downstream straw bale catch dams for any trenching activities.
<br />Temporary drainage and sediment control measures will remain in-place until vegetation is sufficiently established to
<br />effectively control runoff, erosion, and sediment loss.
<br />TR 17-87 2.05-84.7 03/14/17
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